1. Field of the Invention
The present invention relates to telecommunications networks and more particularly to telecommunications networks of the kind requiring communications between the network and terminals attached thereto without provision of a voice communications path at the initial phase of a communications call.
2. Related Art
Many services provided by telecommunications networks will require information additional to a telephone number for example to enable completion of a connection through the transport network. For example, credit or charge card calls may require entry of a personal identification number (PIN) and/or an account number prior to proceeding. Where such services are provided after the customer has been connected through the network to a peripheral a voice or other prompt may be used to request the customer to enter further detail. Such services are therefore often referred to as xe2x80x9cprompt and collectxe2x80x9d services.
Where a customer has a telephone instrument or other terminal adapted to signal the network by use of multi-frequency tones, it is possible for the prompt and collect service to operate by the coding of the tones without establishing a complete speech path through the network. However, many communications connections are not by way of analogue lines to the customer""s premises but are rather of a digital type and, more particularly, of a type known as ISDN in which a single customer connection carries multiple 64 Kbs digital bearer channels and a data channel.
ISDN terminals do not function efficiently in the provision of multi-frequency tones until the terminal is put into a speech phase. However, putting the call into the speech phase prior to effecting a connection simply to enable prompt and collect services to operate may result in charging difficulties as the customer equipment may see a network response as a valid answer.
Further, if the ISDN call originates from a data terminal, ISDN standards do not permit switching back to a data phase after switching into voice phase communication. In many cases also data terminals may not include multi-frequency transmission capability and/or may not include speaker or headset facilities to receive voice prompts.
According to the present invention there is provided a telecommunications network comprising a number of interconnected switching units at least some of which provide switching for ISDN connections, some of said switches being connected to terminals adapted to provide voice channel and data channel communications and to provide switching instructions by way of a data channel connection, control means of the network being responsive to seizure of a switch connection to recognise presence of such a terminal and to cause control means of the switch to effect decoding of data from a data channel associated with the terminal to collect any further control information required by the network.
Preferably, the control means of the network causes the control means of the switch to effect transfer of data channel signalling from a connected ISDN termination through switch means to a prompt-and-collect peripheral adapted to extract control information from transmitted data.
The Prompt-and-collect peripheral may be arranged to transmit data through the switch means for transmission as a data message to a connected ISDN termination to cause display of a prompt message or to cause automated transmission by any terminal connected thereto of data defining required control information.
In one arrangement the prompt-and-collect peripheral is responsive to the control means of the switch to collect data, the control means of the switch effecting transmission of collected data to the control means of the network.
In an alternative arrangement the control means of the switch causes received data to be transmitted to the prompt-and-collect peripheral, the peripheral affecting transmission of collected data to the control means of the network.
According to a feature of the invention there is provided a method of providing prompt and collect services in a digital telecommunications network of the kind in which a received bit stream comprises a plurality of bearer channels and a data channel, the method comprising in respect of each bearer channel initiated call determining from the data channel a network destination; determining from network data relating either to the call source or the network destination whether further data is required from the call source and, if so, causing a data message to be,returned to the call source in the data channel to provide prompt information to a user; and awaiting user information returned in the data channel prior to completing connection of the bearer channel call to the network destination.